FIG. 1 is a perspective view showing a conventional car lamp structure, which includes a bulb portion 700 and a lamp housing 800 that are integrally formed through sinter molding, such as a sinter-molded glass lamp housing, with two electric pins 710 of the bulb portion 700 rearward projected from the lamp housing 800. Each of the electric pins 710 has a connecting strip 720 welded thereto for connecting with external wires (not shown).
The conventional integrally formed car lamp structure as shown in FIG. 1 has the following disadvantages in terms of its manufacture and use: (1) it is troublesome and inconvenient to integrally form the bulb portion 700 and the lamp housing 800 by way of sinter-molding; that is, the bulb portion 700 must be manufactured first, and then the lamp housing 800 and the bulb portion 700 are sintered together; the bulb portion 700 and the lamp housing 800 could not be independently mass-produced and then assembled to each other in a simple manner; and (2) the bulb portion 700 is not replaceable independently; that is, in the event the bulb portion 700 is damaged in the process of manufacturing or burned out while in use, the whole car lamp structure including the lamp housing 800 and the bulb portion 700 must be discarded at the same time to thereby cause waste in material and cost.
To overcome the disadvantages of the conventional integrally formed car lamp structure as shown in FIG. 1, U.S. patent application Ser. No. 12/647,326 entitled “Assembling-type Car Lamp” was filed by the same applicant of the present invention. FIG. 2 is an exploded rear perspective view showing that the assembling-type car lamp disclosed in U.S. patent application Ser. No. 12/647,326 includes a lamp housing 100 and a bulb unit 900. The lamp housing 100 is provided at a predetermined position with an assembling hole 110. A plurality of ribs 120 are circumferentially extended and spaced along an inner wall surface of the assembling hole 110, such that a notch 130 is formed between any two adjacent ribs 120. The bulb unit 900 includes a mounting base 910, a bulb holder 920, and a bulb 930. The mounting base 910 includes a plurality of electric pins 911, an round plate 912, and a raised seat 913 forward projected from the round plate 912. The raised seat 913 is provided on an outer wall surface thereof with a plurality of circumferentially spaced guide blocks 914 located corresponding to the notches 130, such that an annular space 915 is defined between the guide blocks 914 and the round plate 912. The bulb 930 is mounted on the mounting base 910 via the bulb holder 920 and is electrically connected to the plurality of electric pins 911. By aligning the guide blocks 914 on the bulb unit 900 with the notches 130 on the lamp housing 100 and fitting the bulb unit 900 in the assembling hole 110, and then turning the bulb unit 900 for the ribs 120 on the lamp housing 100 to move into the annular space 915 on the bulb unit 900, the bulb unit 900 can be conveniently assembled to the lamp housing 100 for use or for replacement.
However, the assembling-type car lamp disclosed in U.S. patent application Ser. No. 12/647,326 still has the following disadvantages in use: (1) to assemble or disassemble the bulb unit 900 to or from the lamp housing 100, the bulb unit 900 is turned for the round plate 912 to tightly fit in or loosen from the assembling hole 110 on the lamp housing 100. However, the bulb unit 900 is not provided thereon with any portion for a user to properly grip at in order to conveniently turn the bulb unit 900; (2) the bulb 930 is fixedly mounted on the mounting base 910 via the bulb holder 920, and the bulb 930 is fixed in position relative to the bulb holder 920. Therefore, the bulb 930 is not adjustable in its position and focal length; and (3) joints between the bulb 930 and the electric pins 911 are exposed to an outer environment and therefore not dustproof, airtight and watertight.